The invention relates to a method of operating a piston-type internal combustion engine with electromagnetically operated intake and exhaust valves, which, in an engine driven phase above a predetermined engine speed, are all closed at least for one cylinder in order to generate a reduced braking torque.
Environmental factors, noxious emissions and the depletion of fossil fuel resources make it necessary for new power generation concepts to save fuel by increasing the efficiency of the combustion processes of piston internal combustion engines in order to avoid unnecessary energy losses. It is, for example, possible to operate the power plant of a motor vehicle that is, generally, its piston-type internal combustion engine in an intermittent manner by disconnecting the engine from the drive line when the vehicle is in an engine-driven phase and shutting the engine down in such a phase. However, since the engine generally does not only drive the vehicle, but also numerous auxiliary components depend on engine operation such as the cooling and the lubrication system, the electric power supply, the power steering and the power brakes, the intermittent engine operation detrimentally affects these functions. Measures must therefore be taken which compensate for such effects. These measures are generally very expensive under economical and ecological considerations so that, mathematically, a positive result is obtained only after a long period of operation.
It is the object of the present invention to reduce the distance or the amount of time required for an internal combustion engine of vehicles to make economical or ecological measures worthwhile their costs.